The use of high-performance SiGe BiCMOS and nano-scale CMOS technologies in millimeter wave applications has been explored. Some Si-based receivers and transmitters operate up to D-band and in high integration density enabled fully integrated multi-channel arrays. Most of these arrays target either radar and imaging or short-distance data-links at 60 GHz. The antennas for those applications are desired to be low profile, broadside directive, broadband, having low mutual coupling and low cost.
One type of wideband antenna is an aperture coupled patch antenna as described in Analysis of an Infinite Phased Array of Aperture Coupled Microstrip Patches, IEEE Trans. AP, Vol. 37, No. 4, April 1989, Pozar et al. The patch antenna includes a radiating patch printed on a top substrate and a microstrip feed line printed on a bottom substrate. A small aperture in a ground plane couples the radiating patch to the microstrip. This type of antenna, however, has electromagnetic coupling between the feedlines to the radiative elements and tends to have stronger mutual coupling between neighboring elements.